1. Field of the Invention
The present invention relates to a block polymer having a useful function, a polymer-containing composition which contains the block polymer, an ink composition, an apparatus for discharging a liquid using the above-described composition, and a head kit.
2. Related Background Art
Aqueous dispersion materials containing functional substances, e.g., agricultural chemicals such as herbicide and insecticide, medicines such as anti-cancer drugs, antiallergic drugs and antiinflammatory agents, and coloring agents such as ink and toner containing a coloring material, are conventionally well known. In recent years, digital printing technology is making great strides. Digital printing technology, which is represented by the electrophotographic technology and ink-jet technology, is becoming an indispensable imaging technology in offices and home.
Among them, the ink-jet technology is featured by its compactness and low power consumption as a direct recording method. In addition, the image quality has been greatly improved by, for example, the use of fine nozzles. According to one ink-jet method, the ink supplied from an ink tank is heated with a heater in a nozzle to generate a bubble in the ink and an ink droplet is ejected from the nozzle to form an image on a recording medium. Another method discharges ink from the nozzle by the vibration of a piezoelectric element.
Inks used for these methods are usually aqueous dye solutions, so that blurring or a phenomenon called feathering along the direction of paper fiber between superimposed colors at the recorded region on a recording medium may occur. For the purpose of improving them, the use of a pigment dispersion ink is studied in U.S. Pat. No. 5,085,698. However, further improvement is still expected.